Yeah, that's why I was thinking... that his name might be a hint that he's an ally to the protagonists.
In the wiki it says that Shuukichi's name is a reference to Toyotomi Hideyoshi, and the parallel has been highlighted in the manga a few times. In Japanese history, Hideyoshi's closest advisors were his half-brother Hidenaga (also known as Kouichirou) and Kuroda Kanbei. If this is a hint that the person paralleled to Hidenaga is Haneda Kouji, then it could be that superintendent Kuroda fills the spot of Kanbei. Maybe his injury was relevant to the Black Org, but he's not an enemy?
Gosho has introduced characters with samurai names just for the heck of it a few times, but superintendent Kuroda's introduction is really bugging me because his name is "out of place". And he was immediately introduced as a suspect/candidate for Rum, so it feels like this is something to take note of. And speaking of "out of place", Shuukichi is the only person in the Akai family (so far anyway) whose name isn't related to Gundam.